1. Field of the Invention
The present invention generally relates to a communications system having a host exchange and a mate or remote exchange and a method for managing subscriber terminals connected to the remote exchange by the host exchange.
2. Background of the Invention
As a telephone communications service, the communications a subscriber circuit accommodated in a remote exchange is available in which subscriber terminals physically accommodated in the remote exchange are handled as if these subscriber terminals are accommodated in a host exchange coupled to the remote exchange. Hereinafter, subscriber terminals accommodated in a remote exchange are referred to as remote-exchange subscriber terminals. The host exchange manages the same subscriber data and accounting data regarding the remote-exchange subscriber terminals to which the above communications service is provided as if these remote-exchange subscriber terminals are accommodated in the host exchange. Control information concerning the subscriber terminals accommodated in the remote exchange, for example, ON-hook/OFF-hook information is directly transmitted from that exchange to the host exchange via a leased communications line connected between the remote exchange subscriber terminal and the host exchange.
In the above-mentioned manner, the host exchange is capable of handling the subscriber terminals accomodated in the remote exchange as if the subscriber terminals are accommodated in the host exchange.
Conventionally, the host exchange is not informed of a fault occurring in, for example, a subscriber circuit connected between the remote exchange and a remote-exchange subscriber terminal. Further, the host exchange is not informed that a remote-exchange subscriber terminal is maintained in a blocked state in order to, for example, exchange the defective subscriber circuit to which the above remote-exchange subscriber terminal is connected with a new circuit. Since the host exchange is not informed of the above maintenance information, the host exchange cannot detect the situation in which the remote-exchange subscriber terminal is not operable.